Don't forget to check out the Inno Setup newsgroups, the primary source for Inno Setup support (web-based interface available). Additionally, a large number of questions and answers can be found on Stack Overflow.

Extensive support for installation of 64-bit applications on the 64-bit editions of Windows. Both the x64 and Itanium architectures are supported. (On the Itanium architecture, Service Pack 1 or later is required on Windows Server 2003 to install in 64-bit mode.)

Supports creation of a single EXE to install your program for easy online distribution. Disk spanning is also supported.

Standard Windows wizard interface.

Customizable setup types, e.g. Full, Minimal, Custom.

Complete uninstall capabilities.

Installation of files:
Includes integrated support for "deflate", bzip2, and 7-Zip LZMA/LZMA2 file compression. The installer has the ability to compare file version info, replace in-use files, use shared file counting, register DLL/OCX's and type libraries, and install fonts.

Creation of shortcuts anywhere, including in the Start Menu and on the desktop.

Creation of registry and .INI entries.

Running other programs before, during or after install.

Support for multilingual installs, including right-to-left language support.

Yes, it may be used completely free of charge, even when deploying commercial applications. However if you wish to show your appreciation and support its development you can make a donation.

(Note: "Completely free of charge" must not be confused with "completely free". Inno Setup is copyrighted software, not public domain software. There are some restrictions on distribution and use; see the LICENSE.TXT file for details.)